Light emitting diodes (LEDs) are increasingly being used in lighting fixtures, and thus are a very important component of the lighting industry. LED lighting offers advantages over both incandescent and fluorescent lighting. For example, LED lighting is more energy efficient than incandescent bulbs and LED lighting does not have the cold temperature use and mercury issues of fluorescent light bulbs. In addition, the small size of the LEDs allows for creating light bulb packages in ways that incandescent and fluorescent lighting cannot be packaged.
LEDs produce heat which increases the temperature of the LED lighting devices, and if not properly dissipated such heat can reduce the performance and life of the LEDs. Therefore, one challenge to fully commercializing an LED lighting device is to provide a thermal management system that adequately removes heat generated by the LEDs in a cost effective manner. Conduction, convection and radiation are the three means of heat transfer, and therefore some manufacturers attach a heatsink to the LED lighting device in order to reduce the effect of detrimental heat. The heatsink provides a means for removing the energy from the LEDs of the lighting device through convection and radiation of the energy away from the LEDs.
Heat management in LED lighting devices that are becoming smaller, lighter, and more compact is an ever increasing challenge. Conventionally, the heatsink used to dissipate the energy has been made of metals, such as aluminum or copper, which can be machined, cast and/or extruded. In addition, the heatsink used in a particular LED lighting device must be configured so as not to short out signals and/or power being provided to the driver circuitry of the LED lighting device.
FIGS. 1A and 1B illustrate a conventional A19 form factor LED light bulb 100 which includes one or more LED light sources and associated electronic driver components (shown in FIG. 1B). The LED light bulb 100 includes a diffuser 102 connected to a heatsink portion 104, and a base 106 connected to a plastic housing 172 (shown in FIG. 1B). The base 106 is configured to fit into a standard household electrical socket, and includes a neutral connector 108 and a hot contact or tip 110.
FIG. 1B is an exploded view 150 of the conventional A19 form factor LED light bulb 100 of FIG. 1A. As shown, a metal core printed circuit board (MCPCB) 152 is positioned between the heatsink 104 and diffuser 102. The MCPCB contains a plurality of LED light sources 153A-153N situated about the outside edge of the MCPCB, and four LED light sources 153O-153R situated about the middle portion of the MCPCB for producing light output. A reflector 154 is shown positioned for connection to the MCPCB 152 via two self-threading screws 156 and 158. A driver board 160, which includes various electronic components 162 along with wires 164, 166, 168 and 170, is configured to fit within a plastic driver housing 172. As shown, the housing 172 is shaped and/or configured to fit within the heatsink 104, and is also designed to shield the wires 164, 166, 168 and 170 from being electrically short-circuited to the heatsink 104. As mentioned above, the base 106 is configured to fit onto the end of the housing 172, and includes the neutral connector 108 and a hot contact or tip 110.
Referring again to FIG. 1B, during assembly of the A19 LED light bulb the wires 164, 166, 168 and 170 are typically first attached to the driver board 160 and then positioned as shown for further assembly. The driver board 160 is then inserted into the housing 172 and the neutral wire 170 is bent into the slot 173 for connection to the neutral portion 108 of the base 106. In addition, the line wire 168 is positioned for connection to the tip 110 of the base 106. The base 106 is then connected to the plastic housing 172 in hot contact, and the base is then staked to the housing. During this process, care must be taken to ensure that the line wire 168 is in the correct position for attachment to the hot contact or tip 110. In addition, during further assembly, the wires 164 and 166 must be positioned in such manner to connect to the MCPCB 152 to provide power to the LED light sources without causing an electrical short-circuit by contact to the heatsink 104.
The numerous wire-handling operations described above make it difficult to automate the LED lamp assembly process, and can also lead to failures. For example, connection failures can occur between the base (or the driver) and some or all of the wires and the base may not be correctly and/or adequately fitted to the driver housing causing a base torsion failure. Thus, it would be desirable to simplify the wire connections, or eliminate such wire connections, from the LED lamp assembly process while still providing adequate heat dissipation properties.